1.8 Ohms sounds reasonable, in which case the start/stall current, operating from a 12V supply, would be around 6.7 Amps. A 10 Amp motor driver should work.

Or, follow this tutorial for a MOSFET driver http://bildr.org/2012/03/rfp30n06le-arduino/

Contrary to the advice given in that tutorial, you should use a logic level MOSFET, like the one recommended.

Ok so the tutorial makes good sense and all. Now On one of the motors I need to be able to connect the Optical sensor to the Single-head pump. This is what will controll on/off. So I would need to run the sensor in-line with the mosfet between the gate and the arduino?

So the sensor can be found at this link. And if I understand correctly I attach that separately to the Arduino and use the Arduino to read the optical sensor and then based on the reading of the sensor the Arduino talks to the motor?

I really don't have any idea how to properly connect the sensor. The 4 wires are all different. This is why am looking for advice on here. I honestly know nothing about how all of this is supposed to work.